Injector lead question. - Fuel Economy, Hypermiling, EcoModding News and Forum

Recoil · 08-01-2008, 05:28 PM

I know i'm supposed to tap into the wire that has 0v on it, not 12, but what if both leads going to the injector are 12v?

this is with the key on engine off.

looking at the wiring diagram, i'd want the side that runs to the ecu, not the ignition switch, correct?

dcb · 08-01-2008, 05:33 PM

is the injector plug unplugged from the injector when you are measuring? It is "probably" the ecu side you want.

Recoil · 08-01-2008, 05:34 PM

yes, it's unplugged.

& thanks for the quick response!

AndrewJ · 08-22-2008, 04:28 PM

Grrr....

Dealing with the same problem myself. This time on my dad's 93 Geo Prizm (Corolla).

Two wires per injector, both read 0v with ignition off and 12v with ignition on. (Injector unplugged)

I've tapped both leads now for the 'Guino and neither is putting up any numbers for raw data.

Guess I'll go make sure they have the same voltages with the injector plugged in.

Oh, and one more little tidbit. The injectors are ganged up, cylinders 1&3 and 2&4 so the ECU only grounds out one wire to fire two injectors. Dunno how that works with those cylinders being out of sync.

dcb · 08-22-2008, 05:03 PM

Quote:

Originally Posted by AndrewJ

Oh, and one more little tidbit. The injectors are ganged up, cylinders 1&3 and 2&4

Ah, ok, forgot about that, thanks!!

you will have to unplug them in pairs when trying to figure out which lead has the 12 volts, otherwise you will read 12 volts being passed through the other injector that wasn't unplugged.

AndrewJ · 08-24-2008, 03:55 PM

Thanks for the tip dcb, unplugging all the injectors cleared the problem right up when identifying the right wire.

Even though I seem to have tapped the right wire now, I still can't get any fuel numbers to show up on the 'Guino. I even swapped the 'Guino from my car in there and it won't show any data...

So I know it's not the 'Guino, I know the "correct" wire is tapped (I continuity tested it going into the 'Guino just to make sure there's no problem with the wire)

Any other suggestions?

Any parameters I should be looking for that are required for the INJ input? (voltage, frequency, impedence)

dcb · 08-24-2008, 04:16 PM

Can you check that guino ground (on the atmega) is connected to vehicle ground?